Process and device for producing pig iron or liquid steel precursors

ABSTRACT

A process for producing pig iron or liquid primary steel products in a smelting unit ( 1 ), in particular a melter gasifier. Iron-ore-containing charge materials, and possibly additions, are at least partially reduced in at least one reduction unit (R 1 , R 2 , R 3 , R 4 ) by means of a reducing gas. A first fraction of the at least partially reduced charge materials is melted down in the smelting unit ( 1 ), while carbon carriers and oxygen-containing gas are supplied, with the simultaneous formation of the reducing gas. The reducing gas is fed to the reduction unit (R 1 , R 2 , R 3 , R 4 ) and, after the reducing gas has passed through the reduction unit, it is drawn off as top gas. A second fraction of the at least partially reduced charge materials is fed to a smelting reduction unit for reducing and smelting.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. §§371 national phase conversionof PCT/EP2009/055047, filed Apr. 27, 2009, which claims priority ofAustrian Application No. A920/2008 filed Jun. 6, 2008, the contents ofwhich are incorporated by reference herein. The PCT InternationalApplication was published in the English language.

BACKGROUND OF THE INVENTION

The invention relates to a process for producing pig iron or liquidprimary steel products in a smelting unit, in particular a fusiongasifier, in which iron-ore-containing charge materials, in particularfine ore, and possibly additions, are at least partially reduced in atleast one reduction unit by means of a reducing gas.

The invention also relates to an installation for producing pig iron orliquid primary steel products by the process according to the invention,with a smelting unit, in particular a fusion gasifier, and at least onereduction unit for reducing iron-ore-containing charge materials, andpossibly additions, by means of a reducing gas formed in the smeltingunit while carbon carriers, in particular coal, and oxygen-containinggas are supplied.

It is known from the prior art that pig irons or liquid primary steelproducts can be produced in a smelting reduction process. In particular,it is known to use reducing gas that is produced in a smelting unitwhile coal is supplied for reducing iron-containing ores.

To increase the efficiency of such installations, DE 44 21 673 disclosesthat the reducing gas formed in a fusion gasifier can be used in atreated form in a blast furnace, so that the export gas can be used andthe efficiency of the process can be increased. It is disadvantageous inthis case that the export gas has a high calorific value for the blastfurnace, so that the efficiency of the process that is achieved isrestricted. One object of the present invention is to increase furtherthe efficiency of the process, with in particular the amount of coalthat is necessary per tonne of pig iron or liquid primary steel productsbeing lower, so that a smaller amount of carbon dioxide (CO₂) occurs.

This object is achieved by the process according to the invention asclaimed in claim 1 and by the apparatus thereof.

SUMMARY OF THE INVENTION

By the process according to the invention, a first fraction of the atleast partially reduced charge materials is melted down in the smeltingunit while carbon carriers, in particular coal, and oxygen-containinggas are supplied, with the simultaneous formation of the reducing gas.The reducing gas is fed to the reduction unit and, after it has passedthrough the latter, is drawn off as top gas. A second fraction of the atleast partially reduced charge materials is fed to a smelting reductionunit for reducing and smelting. The at least partially reduced chargematerials are also referred to as Low Reduced Iron (LRI), theseintermediate products serve as charge materials for subsequent stages inthe process of iron production or the production of liquid primary steelproducts. It is possible by the process for an at least partiallyreduced charge material, the Low Reduced Iron (LRI), also to beprocessed in a smelting reduction unit provided in addition to thesmelting unit. A considerable proportion of reducing agent is saved inthe smelting reduction unit on account of the reduction that has alreadypartially taken place. Consequently, the overall balance of theproduction of pig iron or liquid primary steel products is reduced withrespect to the process materials that are necessary, in particular thecoal. In addition, the productivity of the smelting reduction unit canat the same time be increased. Of the overall amount of at leastpartially reduced charge materials that is produced, only a firstfraction is processed in a smelting unit, such as for example a fusiongasifier.

According to an advantageous refinement of the process according to theinvention, the amount of the second fraction of the at least partiallyreduced charge materials is established in accordance with the desiredamount of top gas and/or the amount of export gas and/or the quality ofthe export gas. The reducing gas discharged from the at least onereduction unit is referred to as top gas. After appropriate treatment,this top gas may be used as an energy source, it being possible for thetreated gas to be used as an export gas in other processes, such as forexample power generation.

The quality of the export gas is defined by means of gas analysis, thatis to say the composition of the export gas and the resultant calorificvalue. The composition of the export gas depends, inter alia, on theamount of LRI that is produced for example in a smelting reduction unit.The greater the amount of LRI that is produced, the lower the calorificvalue and the amount of export gas. The reason for this is that, when alarge amount of the top gas is reused in the reduction unit, theproportions of carbon monoxide (CO) and hydrogen (H₂) always becomelower and the proportion of CO₂ in the export gas increases. The amountof export gas is reduced, since the proportion of H₂ falls. The higherLRI production has the effect that more H₂ is consumed, resulting inturn in more water (H₂O) being produced. This is separated in the topgas scrubber.

The specific use of the top gas discharged as export gas, and possiblytreated, presupposes that a certain amount is supplied, so that theamount of top gas varies in relation to the amount of reduced LRI and sothe reduction process can be adapted to the requirements of the furtherprocess of processing the top gas.

According to a further advantageous refinement of the process accordingto the invention, the amount of the second fraction of the at leastpartially reduced charge materials (LRI) is 0-1.2 times the amount ofthe pig iron obtained in the smelting unit. If need be, the secondfraction can therefore be taken back to zero or else increased to theextent that it is higher than the amount of pig iron produced in thesmelting unit. On account of the fact that the reducing gas is producedin the smelting unit, it has proven to be technically advisable for theamount of LRI to be varied in the specified range, and consequently anadvantageous match to be found between the reduction unit and thesmelting unit.

According to the invention, the amount of the second fraction of the atleast partially reduced charge materials is 10-60%, in particular20-40%, with reference to the iron fraction of all the Fe carriers thatare charged into the smelting reduction unit. The LRI charged into thesmelting reduction unit substitutes for iron-containing chargematerials. On account of the necessity that reducing materials orfurther process auxiliaries also have to be used in a smelting reductionunit, it has been found to be advantageous if up to a maximum of 60% LRIis used. In this case, the technically conventional percentages relateto the iron fraction of all Fe carriers in the smelting reduction unit.

According to one particular refinement of the process according to theinvention, the degree of reduction in the case of the second fraction ofthe at least partially reduced charge materials and/or in the case ofthe charge materials used in the smelting unit is set to 40-95%, inparticular 65-75%. These degrees of reduction ensure rapid processing ofthe pre-reduced intermediate products in the downstream smelting unit orin the smelting reduction unit, so that the amount of necessary reducingmaterials in these units can be kept low. In addition, the reductionprocess in the reduction unit can be adapted by way of the degree ofreduction or the amount of reducing gas or the composition of thereducing gas, so as to obtain a more flexible process which can bestably conducted with a wide range of parameters.

A special refinement of the process according to the invention providesthat the at least partial reduction of the iron-ore-containing chargematerials takes place in a row of 2 to 6, in particular 3 or 4,reduction units connected in series, the reducing gas being conducted ina countercurrent direction in relation to the iron-ore-containing chargematerials to be reduced. The plurality of reduction units arranged onebehind the other makes it possible for the temperature in the individualreduction units to be controlled more accurately, it being possible forthe temperature control to be adapted to the respective charge materialor the degree of reduction. Moreover, individual units can be operatedas preheating units.

A possible refinement of the process according to the invention providesthat the reduction of the iron-ore-containing charge materials, andpossibly the additions, takes place in at least two mutually parallelrows of reduction units connected in series. The use of two or more rowsof reduction units connected in series allows the amount of reducedcharge materials to be correspondingly adapted or increased, thereducing gas that is produced in the smelting unit always being used.This has the consequence that at least partially reducediron-ore-containing charge materials can be produced in such an amountthat not only the smelting unit but also a smelting reduction unit canbe supplied with them.

According to a preferred refinement of the process according to theinvention, the at least partially reduced charge material is passed onfor compacting, in particular hot compacting, such as for example hotbriquetting. This allows the handling of the reduced charge materials tobe made easier, in particular to avoid re-oxidation and dust developmentin further processing. The compacting has the effect of reducing theporosity and specific surface area of the reduced charge materials, andof largely eliminating the fines. As a result, oxidation is inhibitedduring further processing (transport and storage) and at the same timethe flow behavior of the compacted materials is also improved.Conventional compacting processes take place with hot material, so thatsaid material is not cooled after treatment in the reduction unit butcan be processed directly. This has the consequence that the energybalance is improved and direct processing can take place in thecompacting or subsequently in the smelting unit or in the smeltingreduction unit. In particular, hot briquetting has been found to beadvantageous.

According to a special refinement of the process according to theinvention, the second fraction of the at least partially reduced chargematerials is charged into the smelting reduction unit as an Fe carrier,in particular in place of sinter. Sinter has the disadvantage that itfirst has to be produced on the basis of sinterable iron ores in acomplex process, causing a very considerable occurrence of problematicemissions in the form of gas and dust. Use of the aforementioned secondfraction (LRI) allows a considerable proportion of the sinter to besubstituted. Furthermore, on account of the reduction that has alreadytaken place, it is also possible for the amount of carbon carriers thatis necessary in the smelting reduction unit, in particular coke, to bereduced considerably, so that a significant cost advantage can beachieved.

Particularly advantageously, according to the invention the at leastpartially reduced charge materials may be introduced into the smeltingunit and/or into the smelting reduction unit in a hot state, possiblywith the admixture of cold partially reduced charge materials. Hotcharging allows energy to be saved and the admixing of cold partiallyreduced charge materials allows the temperature of such materials to beadapted during the charging or in the further processing process.

A special refinement of the process according to the invention providesthat the at least partially reduced charge materials are hot-compactedand, to avoid oxidation processes, are cooled, in particular byquenching in a water bath. For the case where it is not intended orpossible for the at least partially reduced charge materials to befurther produced directly, it is necessary to cool the charge materials,in order to avoid oxidation processes, so that said materials can alsobe stored without a protective gas atmosphere. Quenching in a water bathhas been found to be a low-cost variant.

According to a particularly advantageous refinement of the processaccording to the invention, the reduction of the charge materials takesplace in a fluidized bed, in particular a circulating or bubblingfluidized bed, in the reduction unit.

A solid bed through which a stream of fluid flows forms a fluidized bedonce a certain flow rate is reached. At high flow rates, bubbles form inthe fluidized bed.

Depending on the particle shape of the charge materials, the particlesize or the density, a fluidized bed forms with a specific proportion byvolume of solids. The flow rate is in this case lower than the sinkingrate of the particles. A compact suspension layer forms with a surfacethat is churned up by bursting bubbles. Intensive mixing in a verticaldirection is advantageous.

At very high flow rates, there is an increased discharge of finerparticles from the fluidized bed, these particles being returned to thesolids separation by way of a cyclone. The advantages of the circulatingfluidized bed over the bubbling fluidized bed lie in a distinctly higherflow rate, which for example makes efficient reduction processespossible, through intimate mixing of reducing gas and charge material tobe reduced.

The type of fluidized bed is chosen according to the charge materialsand in particular according to the grain size or the grain sizedistribution. Bubbling fluidized beds are used in the case of a grainsize of the charge materials to be reduced of ≦8 mm and an average grainsize d₅₀ of approximately 0.5 to 2.0 mm. Circulating fluidized beds areused in the case of grain sizes of 0.1 to 1 mm and an average grain sized₅₀ of 0.5 mm.

According to an alternative refinement of the process according to theinvention, the reduction of the charge materials takes place in areducing shaft furnace, a rotary tubular furnace or a rotary hearthfurnace, the charge materials being used in the form of pellets and/orlump ore and/or as sinter. This allows different charge materials to beused, using various reduction units.

A further alternative refinement of the process according to theinvention by the reduction of the charge materials taking place onlevels lying one above the other in a multi-level reduction furnace, thecharge materials undergoing restricted guidance by means of a clearer.The restricted guidance allows even charge materials that have atendency to agglomerate to be processed.

According to a special, advantageous refinement of the process accordingto the invention, excess reducing gas is dedusted, scrubbed, possiblymixed with top gas and compressed as recycled gas, fed to a CO₂separation unit, for separation of at least some CO₂ from the recycledgas, and subsequently passed as a product gas into the dedusting deviceor directly into the reduction unit. After scrubbing, which serves forthe separation of solids, after mixing with top gas and after separationof CO₂, excess reducing gas that is not fed directly to a reduction unitcan be re-used as a high-quality reducing gas. In this case, the amountof reducing gas can be increased and the top gas can be passed on for afurther use in addition to use as an export gas.

A special refinement of the process according to the invention providesthat the pressure in the smelting unit is set by means of a scrubber forscrubbing the excess reducing gas. Typically, annular gap scrubbers areused for the scrubbing of the excess reducing gas, so that the counterpressure, and consequently the pressure in the smelting unit, can beeasily set by way of a change in the flow resistance in the scrubber,for example by changing the annular gap.

Particularly advantageously, according to the invention the product gasis heated before it is returned into the dedusting device or directlyinto the reduction unit. Heating allows the process temperature in thereduction unit to be specifically set and for unwanted temperaturechanges to be avoided. The energy balance of the process is therebyimproved.

According to an advantageous refinement of the process according to theinvention, the top gas is cooled and scrubbed before mixing with theexcess, dedusted reducing gas, the heat that is removed from the top gasbeing used for heating the product gas before it is returned into thededusting device or into the reduction unit. The heat of the top gas isused to set the temperature of the product gas; at the same time, thehot top gas is cooled to the extent that it can be passed on for furtheruses or treatment steps.

According to a special variant of the process according to theinvention, the separated CO₂ is discharged together with top gas asexport gas. Usually, the top gas separated in the CO₂ separating unit isdischarged from the CO₂ separating unit as so-called tail gas, theprocess dictating that mostly small amounts of other gases aredischarged with the CO₂. By mixing with some of the top gas, it ispossible to produce a process gas which can be passed on for furtheruses as export gas.

A possible refinement of the process according to the invention isachieved by the amount of recycled gas and the amount of carboncarriers, in particular coal, in the smelting unit being established inaccordance with the amount of the at least partially reduced chargematerials. The amount of coal in the smelting unit establishes on theone hand the temperature in the smelting unit and on the other hand alsothe amount of reducing gas that is available for the reduction.Consequently, the process can be operated by adapting the processmaterials, such as for example the coal, within a wide range ofparameters or range of amounts.

According to the invention, the reducing gas is partially combusted inthe reduction unit while oxygen is supplied to set the temperature ofthe reduction unit. As a result, it is possible to specifically set orvary the temperature of the reduction unit, and thereby the processtemperature in the reduction unit. If a plurality of reduction units areused, a partial combustion may take place in each reduction unit, sothat each reduction stage can be influenced with respect to itstemperature and the reducing capability of the reducing gas.

A suitable refinement of the process according to the invention providesthat the charge materials are mixed with additives, in particularlimestone, burnt lime, hydrated lime, dolomite, burnt or hydrateddolomite or quartz, and preferably dried before being charged into theat least one reduction unit, the charge materials and the additiveshaving approximately the same grain size. The advantageous mixing withthe auxiliaries makes largely homogeneous reduction possible, the grainsizes having to be adapted in such a way that short reduction times anduniform reduction can be ensured. In the case of high, critical moisturecontents of the charge materials (typical values for a moisture contentof over 8%), energy consumption in the reduction unit is reduced byprior drying. It has also been found that drying is also advantageous incases of lower moisture contents (as from a moisture content ofapproximately 4%), since this ensures that the charge materials can flowin the transporting systems and feed containers. In cases of lowermoisture contents, the charge materials can also be used without priordrying.

With the apparatus according to the invention, the capacity of thereduction units can be adapted in such a way that a greater amount ofreduced charge material is obtained with a smelting unit that alsoserves as a reducing gas generator. The hot compacting upstream of thesmelting unit allows at least partially reduced charge materials in lumpform to be produced, forming a high-quality charge material for pig ironproduction. On the basis of at least two parallel rows of reductionunits connected in series, the installation can be operated veryflexibly. It is usual here to have rows with 3 or 4 reduction units. Forexample, for servicing work it is possible to operate just one row ofthe reduction units, while the other row is being serviced. Furthermore,it is conceivable to adapt the amount of at least partially reducedcharge material within a wide range, the amount of carbon carriers nothaving to be increased, or only slightly.

A possible variant of the installation according to the inventionprovides that one of the devices for hot compacting is in connectionwith a charging container or a reduction shaft, for receiving or furtherreducing the compacted, at least partially reduced charge materials,this container or shaft being arranged above the smelting unit, so thatcharging into the smelting unit is possible. The use of a reductionshaft for the charging into the smelting unit allows oxidation of thecompacted and at least partially reduced charge material to be avoided,even if there are delays in the charging into the smelting unit. A verysimple solution is obtained by using a charging container, it also beingpossible here to provide a shielding gas to avoid oxidation processes.The charging of the charging container or from the reduction shaft maytake place with the aid of discharging elements such as conveyingscrews, clearers or rotary cell transfer units by gravitational force orelse by transporting devices.

According to a special variant of the installation according to theinvention, at least one of the devices for hot compacting is connectedto a device for quenching the compacted, at least partially reducedcharge materials. The direct quenching and associated cooling allowsunwanted oxidation processes to be avoided; this distinctly increasesthe time for which the at least partially reduced charge materials canbe stored.

According to a particularly advantageous embodiment of the installationaccording to the invention, one of the devices for hot compacting iscoupled to a smelting reduction unit, in particular a blast furnace, anelectric low-shaft furnace or a liquid bath furnace in such a way thatthe compacted, at least partially reduced charge materials can beintroduced into the smelting reduction unit. Consequently, the smeltingunit is coupled to the reduction unit or units and to a further smeltingreduction unit, so that flexible charging into the smelting unit or thesmelting reduction unit is possible. Altogether, the coupling of theunits allows pig iron production with a distinctly smaller amount of CO₂to be achieved. The type of furnace can be chosen according torequirements, so that with most existing installations a combination ispossible, for example by adding a smelting unit and the reduction unitor units.

A possible embodiment of the installation according to the invention isachieved by the smelting unit being connected by way of a line to adedusting device, in particular a dry dedusting device, preferably acyclone or a reduction cyclone, for the separation of dusts from thereducing gas, it being possible for the dedusted reducing gas to be fedto the rows of reduction units by way of a reducing gas feed line. Thededusting allows the quality of the reducing gas to be improved byeliminating fines and dusts. The use of a dry dedusting device makes itpossible to keep down the cooling of the reducing gas, so that said gascan be fed to the reduction unit or units largely without any furtherheating.

A further possible embodiment of the installation according to theinvention is achieved by the reducing gas feed line being connected to ascrubber for excess reducing gas in such a way that reducing gas that isnot required in the reduction units can be discharged and scrubbed. Inthis way it is possible to lead off some of the reducing gas and treatit separately, in particular by a scrubber, so that solids are largelyeliminated. The excess, cleaned reducing gas can then be passed on forfurther uses.

According to a particularly advantageous embodiment of the installationaccording to the invention, the scrubber is connected by means of arecycled gas line to a CO₂ separating unit, in particular on the basisof an adsorption process with a pressure change or an absorptionprocess, for the separation of CO₂ from the scrubbed reducing gas, itbeing possible for the product gas thereby formed to be fed by way of aproduct gas line to the dedusting device or the reduction units.

The CO₂ separating unit may be used on the basis of various technologiesor the processes mentioned; apart from the physical absorptionprocesses, such as for example the rectisol process on the basis of coldmethanol as a solvent, chemical absorption processes can also be used,such as the MEA process on the basis of monoethanolamines and the DEAprocess on the basis of diethanolamines or else the Benfield process onthe basis of potassium carbonate with an inhibitor. As an alternative tothese known processes, it is also possible to use adsorption processes,using in particular pressure changing processes that use a selectiveadsorption behavior of a molecular sieve in dependence on pressure. Itis particularly advantageous in this respect if the lower pressure stageis operated at subatmospheric pressure, as is usual with vacuum pressurechanging processes.

According to an advantageous embodiment of the installation according tothe invention, at least one of the rows of reduction units is connectedby way of a top gas discharge line to the recycled gas line, so that thetop gas discharged from the reduction units can be mixed with thescrubbed excess reducing gas and fed by way of a compressor to the CO₂separating unit. By the inclusion of the top gas, it is possible to freethe excess reducing gas and the top gas of CO₂ and thereby generate areducing gas that has a high reduction capability. The product gasobtained in this way can be used again as a high-quality reducing gas inthe reduction unit or units, so that a greater amount of chargematerials can be reduced without more carbon carriers having to be usedin the smelting unit.

A particularly advantageous embodiment of the installation according tothe invention is achieved by the top gas line and the product gas lineeach having at least one heat exchanger for cooling the top gas and forheating the product gas, it being possible for the heat removed from thetop gas to be fed to the product gas. In this way it is possible toextract heat from the top gas and thereby correspondingly cool the veryhot top gas and to heat the product gas before it is introduced into thereduction units.

According to an advantageous embodiment of the installation according tothe invention, at least one oxide dryer is provided for mixing anddrying the iron-ore-containing charge materials, and possibly theadditions, said dryer being connected by way of transporting devices andfeed containers to the rows of reduction units. The drying and mixingachieves a homogeneous mixture, which makes uniform reduction in thereduction units possible.

The invention is described hereafter by way of example on the basis of anon-restrictive exemplary embodiment and the figures.

BREIF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the process diagram of a fine-ore direct reducing/smeltingprocess

FIG. 2 shows a process diagram of a fine-ore direct reducing processaccording to the invention

FIG. 3 shows a process example on the basis of an installation accordingto the invention with a pressure changing process for CO₂ separation incombination with a blast furnace

FIG. 4 shows a process example on the basis of an installation accordingto the invention with a vacuum pressure changing process for CO₂separation in combination with a blast furnace

DESRCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 shows a process diagram and the installation for a directreducing/smelting process for fine ores. In a smelting unit, such as forexample a fusion gasifier 1, an at least partially reduced fine ore ismelted down while carbon carriers, such as for example coal, are added,thereby forming reducing gas which is introduced into the row ofreduction units R1 to R4 connected in series. The reducing gas therebyflows in countercurrent in relation to the fine ores to be reduced, andpossibly additions, which are mixed and dried before being fed into thereduction unit R4. The at least partially reduced fine ore is made intolump form in a hot compacting unit 12 and introduced into the chargingcontainer 21, mostly while still hot, and smelted in the smelting unit 1into pig iron RE. The charging container may also be configured as areduction shaft. Further details of the treatment of the reducing gasare explained in more detail on the basis of FIG. 2.

FIG. 2 shows a process diagram and an installation for the directreducing/smelting process for fine ores according to the invention. Theinstallation has two rows of reduction units R1 to R4, In each row , thereduction units are connected in series. The two rows are arranged andconnected in parallel to one another, so that, by analogy with thediagram that is shown in FIG. 1, the reducing gas is conducted in thereduction units in countercurrent in relation to the charge materialsthat are at least partially reduced by the reducing gas. Both rows aresupplied with reducing gas from the smelting unit 1 by way of reducinggas lines.

The process according to the invention can also be operated, however,with an installation according to FIG. 1, wherein the reduction is onlyoperated in one row of reduction units connected in series.

The reducing gas is generated by adding carbon carriers, such as lumpcoal K or fine coal FK or coal dusts KS into the smelting unit 1. Finecoal or coal dusts are in this case injected into the smelting unit. Thepig iron RE is drawn off from the smelting unit 1 together with slag.

After cleaning the reducing gas in a dry separating device, such as forexample a cyclone 2, the reducing gas is fed to the reduction units.Solids separated in the separating device 2 are returned into thesmelting unit 1.

After cleaning in the separating device 2, excess reducing gas is fed toa scrubber 3 and cleaned further. The scrubber may be configured forexample as an annular gap scrubber, it being possible for the flowthrough the scrubber to be regulated by setting the annular gap, so thatthe pressure in the smelting unit 1 can be regulated by way of thescrubber 3.

The scrubbed reducing gas can then be mixed with top gas, which is drawnoff from the reduction unit R4, and fed as recycled gas to a CO₂separating device 5 by means of a compressor 4. Separated gas fractionsthat predominately comprise CO₂ are discharged as tail gas by way of thetail gas line 6, the tail gas line 6 opening into the export gas line 7,so that excess top gas can be discharged together with tail gas asexport gas EG. The recycled gas cleaned of CO₂ is conducted as productgas by way of the product gas line 8 either into the separating device 2or directly into the reduction units R1.

The top gas may be cooled by means of a heat exchanger 9, 9 a, the heatextracted thereby being fed to a heat exchanger 10 and used for heatingthe product gas. Furthermore, after cooling in the heat exchanger, thetop gas may be cleaned in scrubbers 16, 16 a.

The reducing gas, and possibly also product gas, are fed to thereduction units R1. These gases flow through the reduction units incountercurrent in relation to the charge materials E, and possibly theadditions Z. The reduction unit R4 is operated as a preheating unit forpreheating the charge materials and the additions. The charge materialsand the additions are first mixed and dried in an oxide dryer 11 and fedby way of suitable devices to the reduction units R4.

The at least partially reduced charge materials, and possibly theadditions, are discharged from the reduction units R1 of the two rowsand fed to two devices for hot compacting 12 and 13, so as to produce aproduct in lump form, such as for example briquettes.

This product may be fed to a device for quenching 14, such as forexample a quenching basin, and cooled, so that oxidation processes canbe avoided. The product in lump form that is produced in the reduction,comprising at least partially reduced charge materials, such as fineores, in particular fine iron ores, and possibly additions, is referredto as Low Reduced Iron (LRI) and represents a high-quality chargematerial for smelting reduction processes.

The LRI can be charged in a hot state directly into a smelting reductionunit 15, this advantageously being a blast furnace. Alternatively, coldLRI or mixtures of hot and cold LRI may also be charged into thesmelting reduction unit. The at least partially reduced chargematerials, and possibly the additions, may be introduced into thesmelting reduction unit as briquettes or in some other lump form as Fecarriers in place of sinter, so as to dispense with the need for atleast some of the sinter. This makes it possible for large amounts ofsinter and/or pellets and/or lump ore to be saved in the sinteringprocess at the sintering installation. The saving of sinter isparticularly advantageous, since the exhaust gases occurring duringsintering, and the coke required therefor, can be distinctly reduced.Furthermore, the amount of coke required in the blast furnace can alsobe reduced, since the LRI introduced in place of the sinter lowers thespecific energy consumption. At the same time, the reduced specific cokeconsumption allows the specific output of the blast furnace to beincreased. A possible process route is presented below by way of exampleon the basis of an actual example according to FIG. 3.

The installation comprises a row 19 of reduction units connected inseries, which are in connection with a smelting unit, in the actual casewith a fusion gasifier 1.

This plant is known as a FINEX® installation 18. In addition, the fusiongasifier 1 is in connection with a further row 21 of reduction unitsconnected in series. The at least partially reduced charge materials andadditions produced in this row are referred to as Low Reduced Iron(LRI). This plant 20 is correspondingly referred to as the LRIinstallation. The LRI installation is similarly operated with reducinggas from the fusion gasifier 1, so that the two rows of reduction unitsare operated substantially parallel to one another. The LRI usually hasa degree of reduction of 60 to 70%.

Concentrates of ores 22, in particular iron ores, come intoconsideration as charge materials, producing an ore concentrate on thebasis of naturally occurring ores with enrichment of the iron oxides.Apart from the concentrates, sintered ores 23 are used. These are oreswhich are usually added to a sintering installation and have small grainsizes, that is to say are to be classified as fine ores.

Furthermore, coal 24 and additions 25 are used, the coal being chargedinto the fusion gasifier to generate the reducing gas and to smelt thepig iron.

On the basis of annually

-   -   4 million tonnes of concentrate    -   1.7 million tonnes of sintered ore    -   1.7 million tonnes of coal    -   0.7 million tonnes of additions    -   130 000 Nm³/hour of oxygen from the oxygen installation 17,        it is possible to produce per year approximately    -   2 million tonnes of pig iron and    -   2.2 million tonnes of LRI;        the 2.2 million tonnes of LRI can be fed to a smelting reduction        unit, such as for example a blast furnace, as a substitute for        sinter. In addition, an export gas EG with an energy content of        approximately 364 MW is produced and can be passed on for        external use, for example in a power generating plant. On the        basis of the LRI and sinter, coke and additions, approximately 4        million tonnes of pig iron can consequently be produced in a        blast furnace.

Use of the LRI in the blast furnace makes it possible to substitute upto 60% of sinter with LRI, it being possible for this to be increasedfurther by adaptations to the operating mode of the blast furnace. As aconsequence, the sintering installation can be made to smallerdimensions or sintering exhaust gases and coke required for thesintering can be reduced.

A further advantage is that the amount of coke required in the blastfurnace can be correspondingly reduced; using LRI for 40 to 50% of theiron fraction of all the Fe carriers, approximately 150-200 kg of cokeper tonne of pig iron can be saved. Operating the FINEX® installationwith the LRI installation and a blast furnace, approximately 25-40% ofthe total amount of pig iron is produced by means of the smelting unitof the FINEX® installation and approximately 60-75% is produced by meansof the blast furnace. Apart from the reduced consumption of coke andcarbon carriers overall, less export gas occurs in the case of theprocess according to the invention, so that an altogether more efficientprocess with lower environmental impact can be ensured. Consequently,considerable cost advantages per tonne of pig iron produced can beachieved. The amounts specified are influenced by the type of CO₂separating device that is used.

In FIG. 4, the effect of a modified CO₂ separating device isrepresented. A vacuum pressure changing process is used in place of apressure changing process for the separation of CO₂ from the recycledgas, so that the amount of LRI that can be produced by the installationcan be increased considerably. With adaptation of the amounts ofconcentrate, sintered ore and additions, the amount of LRI is therebysuccessfully increased from approximately 2.2 million tonnes to 2.8million tonnes, while allowing the amount of export gas to be reduced.The necessary amount of carbon carriers remains unchanged. The calorificvalue of the export gas EG is reduced when the vacuum pressure changingprocess is used.

The process thereby uses a still more effective separation of CO₂, whichis achieved by lowering the minimum pressure to virtually the level of avacuum.

The invention claimed is:
 1. A process for producing pig iron or liquidprimary steel products in a melter gasifier and a smelting reductionunit, comprising: at least partially reducing iron-ore-containing chargematerials in at least one reduction unit by means of a reducing gas,melting a first fraction of the at least partially reduced chargematerials in the melter gasifier and also supplying carbon carriers, andoxygen-containing gas to the melter gasifier for simultaneous formationof the reducing gas, feeding the reducing gas to the at least onereduction unit and, after the reducing gas has passed through thereduction unit, drawing off the reducing gas which has passed throughthe reduction unit, as top gas or as export gas, and feeding a secondfraction of the at least partially reduced charge materials, Fe carriersother than the second fraction of the at least partially reduced chargematerials, and carbon containing reducing materials to the smeltingreduction unit for reducing the second fraction of the at leastpartially reduced charge materials and smelting it, wherein the amountof the second fraction of the at least partially reduced chargematerials is 10-60%, with reference to an iron fraction of all Fecarriers that are charged into the smelting reduction unit.
 2. Theprocess as claimed in claim 1, wherein the amount of the second fractionof the at least partially reduced charge materials is established inaccordance with at least one of: a selected amount of top gas, theamount of export gas, and the quality of the export gas.
 3. The processas claimed in claim 1, wherein an amount of the second fraction of theat least partially reduced charge materials (LRI) is up to 1.2 times anamount of pig iron obtained in the melter gasifier.
 4. The process asclaimed in claim 1, wherein a degree of reduction in at least one of:(1) the second fraction of the at least partially reduced chargematerials and (2) the charge materials used in the melter gasifier isset to 40-95%.
 5. The process as claimed in claim 1, wherein the atleast partial reduction of the iron-ore-containing charge materials isperformed in a row of 2 to 6 reduction units connected in series, thereducing gas being conducted in countercurrent in relation to theiron-ore-containing charge materials to be reduced.
 6. The process asclaimed in claim 1, wherein the reduction of the iron-ore-containingcharge materials is performed in at least two mutually parallel rows ofthe reduction units, the reduction units in each row of the at least twomutually parallel rows being connected in series.
 7. The process asclaimed in claim 1, further comprising passing along the at leastpartially reduced charge material from the at least one reduction unitand then compacting it.
 8. The process as claimed in claim 1, furthercomprising charging the second fraction of the at least partiallyreduced charge materials into the smelting reduction unit in place ofsinter.
 9. The process as claimed in claim 1, further comprisingintroducing the at least partially reduced charge materials into atleast one of: (1) the melter gasifier and (2) the smelting reductionunit in a hot state.
 10. The process as claimed in claim 1, furthercomprising hot compacting the at least partially reduced chargematerials then cooling the at least partially reduced charge material toavoid oxidation processes.
 11. The process as claimed in claim 1,wherein the reduction of the charge materials is performed in afluidized bed in the at least one reduction unit.
 12. The process asclaimed in claim 1, wherein the reduction of the charge materials takesplace in a reducing shaft furnace, a rotary tubular furnace or a rotaryhearth furnace, and wherein the charge materials are in the form of atleast one of: (1) pellets, (2) lump ore, and (3) sinter.
 13. The processas claimed in claim 1, wherein the reduction of the charge materialstakes place on levels lying one above the other in a multi-levelreduction furnace, and the charge materials undergo restricted guidanceby means of a clearer.
 14. The process as claimed in claim 1, furthercomprising dedusting the reducing gas drawn off from the meltergasifier, in a dedusting device, and feeding the dedusted reducing gasto the at least one reduction unit.
 15. The process as claimed in claim1, further comprising partially combusting the reducing gas in the atleast one reduction unit while supplying oxygen to set a temperature ofthe reduction unit.
 16. The process as claimed in claim 1, furthercomprising mixing the charge materials with additives, selected from thegroup consisting of limestone, burnt lime, hydrated lime, dolomite,burnt or hydrated dolomite and quartz, and drying the mixture beforecharging it into the at least one reduction unit, wherein the chargematerials and the additives have approximately the same grain size. 17.A process for producing pig iron or liquid primary steel products in amelter gasifier and a smelting reduction unit, comprising: at leastpartially reducing iron-ore-containing charge materials in at least onereduction unit by means of a reducing gas, melting a first fraction ofthe at least partially reduced charge materials in the melter gasifierand also supplying carbon carriers, and oxygen-containing gas to themelter gasifier for simultaneous formation of the reducing gas, feedingthe reducing gas to the at least one reduction unit and, after thereducing gas has passed through the reduction unit, drawing off thereducing gas which has passed through the reduction unit, as top gas oras export gas, feeding a second fraction of the at least partiallyreduced charge materials and Fe carriers other than the second fractionof the at least partially reduced charge materials to the smeltingreduction unit for reducing and smelting, wherein the amount of thesecond fraction of the at least partially reduced charge materials is10-60%, with reference to an iron fraction of all Fe carriers that arecharged into the smelting reduction unit, dedusting the reducing gasdrawn off from the melter gasifier, in a dedusting device, and feedingthe dedusted reducing gas to the at least one reduction unit, anddedusting and scrubbing excess reducing gas and compressing the reducinggas as recycled gas, feeding the recycled gas to a CO₂ separation unitand separating at least some CO₂ from the recycled gas, and subsequentlypassing the recycled gas as a product gas into the dedusting device ordirectly into the reduction unit.
 18. The process as claimed in claim17, further comprising setting the pressure in the melter gasifier by asetting means of a scrubber for scrubbing the excess reducing gas. 19.The process as claimed in claim 17, further comprising heating theproduct gas before it is returned into the dedusting device or directlyinto the at least one reduction unit.
 20. The process as claimed inclaim 17, further comprising cooling and scrubbing the top gas beforemixing the top gas with the excess, dedusted reducing gas, removing heatfrom the top gas and using the removed heat for heating the product gasbefore it is returned into the dedusting device or into the at least onereduction unit.
 21. The process as claimed in one of claims 17, whereinthe separated CO₂ is discharged together with top gas as export gas. 22.The process as claimed in claim 17, further comprising setting theamount of recycled gas and the amount of carbon carriers in the meltergasifier in accordance with the amount of the at least partially reducedcharge materials.